Retired Marine Gen. John Allen said fewer troops could remain in Afghanistan after 2014 than he initially recommended to accomplish U.S. goals. (The Associated Press)

The former top commander in Afghanistan said he initially recommended that 13,600 U.S. troops remain in the country when the American combat role there ends after 2014, but believes the mission could still be accomplished with less.

"I always believed that was the number that I should recommend," retired Marine Gen. John Allen said of the 13,600 recommendation. A lower number would accomplish the job, but require more assistance from allies, he said.

The issue of what size residual force to leave in Afghanistan has been the subject of debate as the United States grapples with winding down a war that has lasted more than 10 years.

"The question is if you get a number less than that can you still accomplish the mission," Allen said. "I believe there was a number less than that that could still accomplish the mission with acceptable risk." Allen declined to specify the lesser number.

However, the German defense minister said after a NATO meeting in February that then-Defense Secretary Leon Panetta said he envisioned between 8,000 and 12,000 troops in Afghanistan after 2014.

The White House has not reached a decision on numbers.

Republicans, such as Sen. John McCain, have accused the Obama administration of accelerating the pace of the drawdown too quickly, potentially jeopardizing military gains by not leaving a robust force behind. The Afghans also have expressed worries about being abandoned.

Marine Gen. Joseph Dunford, who assumed command in February from Allen, said recently that he has not yet made a recommendation but would see how Afghan security forces perform as a new fighting season opens.

This is the first fighting season with Afghan security forces leading most operations. "I believe this summer will be the bellwether for Afghan performance into 2014," Dunford told the Senate Armed Services Committee recently.

After 2014, U.S. forces will provide advisers for the Afghan security forces and a counterterrorism force capable of targeting al-Qaida militants. U.S. allies are also expected to contribute to the adviser mission.

Coalition advisers will be embedded in the Defense and Interior ministries and at the corps level, where top-level operations are planned, around the nation. Coalition forces will also be required to provide security for some U.S agencies that remain in Afghanistan.

"The United States has been very clear: We are going to put a military force into Afghanistan post-2014 to train, advise, assist and conduct (counterterrorism)," Allen said. "That is a certainty."

Dunford and Allen said the specific number of forces is less critical than assuring the Afghans that the United States and its allies will not abandon them when the combat mission ends at the end of 2014.

The current climate of uncertainty worries the Afghans, Allen said.

"In the absence of clarity of what the post-2014 period will look like we are going to see increasingly, I believe, a hedging strategy," Allen said.

The climate of uncertainty makes businesses less willing to invest and neighboring countries hesitant to support a peace process, Allen said. Women, who were severely repressed under the Taliban and have since won back a number of rights, are also worried.

"I know they are very concerned about having clarity about the future," Allen said.

"The longer we don't have that clarity, the more difficult it will be to walk back those hedging strategies," Allen said.

Allen, who stepped down from the Afghanistan command in February, is officially retired from the Marine Corps.